The Ge = N bond of 1 adds hydrogen chloride, ethanol, tertbutyl alcohol, methyllithium, and methyl iodide to form 3-6 and 8. The Ge = S bond in 2 analogously adds methyl iodide to yield 10. In the resulting products the electropositive part of the polar reactand is bound to nitrogen or sulfur, while the electronegative one is on the germanium atom. In the lithium derivative 6 and in the iodine derivative 8 Li and I can be replaced by hydrogen to form two isomers of the same composition 7 and 9, which differ only in the positions of the hydrogen and methyl groups with respect to Ge or N. The X-ray structure analyses on 4, 9, and 10 reveal that the germanium atom is fourfold coordinated by two nitrogen atoms and two other ligands. The intramolecular nitrogen base of the silazyl moiety in 1 and 2 is, thus, expelled from the coordination sphere of germanium by insertion of the double bonds into polar sigma-bonds, and the tricyclic molecule is changed to a bicyclic one. Thus these "base stabilized pi-bonds" in 1 and 2 behave as normal unsaturated systems.
